Safety Trial of the RedDress Wound Care System (RD1) in Management of Texas 1a or 2a Neuropathic Diabetic Foot Ulcers.: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Safety Trial of the RedDress Wound Care System (RD1) in Management of Texas 1a or 2a Neuropathic Diabetic Foot Ulcers. (NCT01396837), a na phase 2 study. The primary outcome is Number of Participants Experiencing Adverse Events.

2. Clinical Question

The registry frames the trial’s purpose as assessing the safety of RD1 in this ulcer population. That framing matters: the main question concerns events observed during treatment and follow-up, not whether RD1 is more effective than another treatment. The record lists wound closure at 12 weeks and reduction in wound size over 12 weeks among the secondary outcomes, along with complications due to lack of venous access. Those outcomes do not create a control group or change the single-group nature of the study.

The group enrolled 20 participants. The reported adverse-event counts describe what occurred in that group; they do not by themselves show what would have happened without RD1, under usual care, or with another intervention. Nor do counts alone establish that an event was caused by the device. The registry record does not report a comparative estimate or a causal analysis. The appropriate reading is therefore descriptive: these are safety observations from a small, open-label, single-group trial over the stated follow-up period.

3. Trial Design

This was a Phase 2, multicenter, prospective, open-label safety trial of the RedDress Wound Care System (RD1). Its design is listed as single-group, with no masking and allocation marked not applicable. The registry lists an enrollment of 20 participants. The study status is completed; its recorded start is 2014-05 and its primary completion is 2016-08.

All participants were assigned to the RD1 group as represented in the registry record. There was no randomized allocation and no separate control arm. The registry specifically identifies the trial as not being a randomized comparison, so differences between treatment arms cannot be assessed. A single-group safety study can describe events in participants receiving the intervention, but it cannot distinguish those events from events that might have arisen from the underlying condition, other care, or chance.

The intervention is described as a biologic autologous product made from the participant’s whole blood at the point of care with the RD1 kit. The primary outcome is the number of participants experiencing adverse events over 12 weeks in the intention-to-treat population. Its description encompasses serious adverse events, adverse events including lack-of-venous-access events, and device-related adverse events. The registry also lists secondary outcomes for lack-of-venous-access complications, complete wound closure at 12 weeks, and wound-size reduction over 12 weeks.

The record lists four outcome measures and no analysis entries. It does not report masking procedures beyond the study being open label, the detailed visit schedule, the criteria used to determine eligibility, or the planned statistical analysis. Those elements should not be inferred from the trial’s title or the outcome descriptions. The enrollment and follow-up information describe the study as registered; they do not establish that every participant completed all follow-up or had complete data for every outcome.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

Overall Study

Analysis population for the primary outcome, as defined in the registry: ITT population

5. Baseline Characteristics

The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.

6. Primary Endpoint

The registry lists the primary outcome as Number of Participants Experiencing Adverse Events, measured over 12 weeks.

The primary endpoint counts participants who experienced adverse events during the 12-week timeframe. It is a participant-count outcome, rather than a measure of the number of event episodes or their duration. The registry states that the adverse-event rate is to include serious adverse events, adverse events including any lack-of-venous-access events, and device-related adverse events. The listed endpoint population is the intention-to-treat population.

Safety outcomes are used to describe the types and frequency of unwanted events observed while an intervention is being studied. Counting affected participants can make the summary more directly interpretable than a list of event episodes, because a participant with repeated events is not necessarily counted as multiple affected participants. However, the registry record does not provide a separate episode count or clarify how repeated events are handled in every reported category.

The posted group results report 3 participants with serious adverse events and 16 with other adverse events. These counts are not a comparative treatment effect, and they do not establish that RD1 caused the events. The endpoint description refers to the intention-to-treat population, while also mentioning the safety population in the description of how adverse-event rates will be calculated. A separate safety-population result is not reported in the registry record. Nor are confidence intervals or a detailed account of event ascertainment reported, limiting the precision and context available for interpreting the count.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Several statistical ideas help frame the registry’s safety results. The key distinction is between a descriptive count and an estimate of a treatment effect. A count tells how many participants in the observed group experienced an event. A treatment effect compares outcomes under different treatment conditions, usually using a control group or another defensible comparison. This trial is listed as single-group with allocation not applicable, so the reported counts are not comparative effects.

What a participant count represents

A participant-count endpoint records whether each participant experienced the outcome during the stated period. In general, this type of endpoint is useful when the question is how many people were affected, rather than how many total episodes occurred. One participant may experience more than one event, but a count of participants affected does not necessarily show the number of episodes. The registry reports participants with serious adverse events and participants with other adverse events; it does not report episode totals or explain the handling of recurrent events in detail.

Categories can overlap. If a participant experienced both a serious event and another adverse event, that person could potentially be represented in more than one category, depending on the registry’s coding. Since the record does not clarify overlap, the two counts should not be summed to create a total number of distinct participants. A percentage can describe a count relative to a defined denominator, but no aggregate percentage for the primary endpoint is reported in the registry record. The percentages attached to individual serious-event terms are reported as such and should not be reinterpreted as an overall adverse-event percentage.

Why uncertainty matters

A count observed in a study is subject to sampling variability: another group of participants could yield different counts even if the underlying conditions were similar. In general, a confidence interval expresses uncertainty around an estimated quantity by giving a range of values compatible with the data under the method’s assumptions. It is not a guarantee that the underlying value lies within that range, nor does it address every source of bias. No confidence intervals for the adverse-event results are reported in the registry record, so their statistical precision cannot be evaluated directly.

Small studies generally offer limited information about uncommon events. A study may observe no instances of a particular event, or only a few, without ruling out that the event could occur in a larger population. Here, the record lists an enrollment of 20, but does not provide a formal precision target for the safety endpoint. It also does not report a sample-size justification. Therefore, the enrollment should not be interpreted as proof that the study was large enough to identify all safety concerns.

Why a control group changes interpretation

In a randomized comparison, allocation aims to create groups that can be compared while reducing systematic differences in measured and unmeasured factors. This trial did not use randomized allocation and has no separate comparator group. As a result, the observed counts cannot be contrasted with a control-arm count, and they do not estimate the difference in event risk between RD1 and another treatment. Comparing these results informally with another study would also be unreliable unless differences in participants, follow-up, outcome definitions, and event collection were addressed.

The study is open label, meaning masking is listed as none. In general, knowledge of treatment assignment can affect care and the reporting, elicitation, or classification of outcomes, especially for outcomes that require judgment. The record does not describe event-adjudication procedures or provide enough information to assess whether the open-label design affected ascertainment. This is a possible design consideration, not evidence that the reported events were misclassified.

Planning calculations are not trial findings

Planning illustrations based on an observed effect answer a different question from the trial’s observed results. In general, a power calculation estimates a sample size under specified assumptions about a target effect, significance level, allocation, and statistical model. Such a calculation is prospective planning information; it is not evidence that the study had a particular probability of detecting an effect after the results were known. The record’s planning assumptions describe a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and an effect defined as a stated fraction of an observed effect. Those assumptions do not describe this single-group trial’s design. Any associated sample sizes are planning illustrations, not observed power or trial results.

Over-dispersion is a general statistical concern when outcome variability exceeds what a simple model assumes. If ignored, standard errors may be too small and uncertainty may appear narrower than warranted. This concept can matter for certain count outcomes, particularly when event counts vary widely across participants. The primary endpoint is described as a count of participants with an event, not a count of event episodes; the registry record does not report a model or dispersion assessment. It would therefore be inappropriate to claim that over-dispersion was assessed or affected the analysis.

Finally, a registry outcome description is not a complete statistical analysis plan. The record lists four outcome measures and no analysis entries, and it does not report the methods used to estimate uncertainty, handle missing outcomes, adjust for multiple outcomes, or analyze the secondary measures. Those methods should be treated as not reported in the registry record rather than inferred from common practice.

10. Exact Estimates for Each Arm

No two-arm comparison is shown for this trial, but each arm's result can still be summarized with exact interval estimates computed from the posted counts. The Clopper-Pearson interval is exact and conservative; the Wilson interval is a common closer-to-nominal alternative; the Bayesian credible interval uses a uniform Beta(1, 1) prior. For small groups the three can differ noticeably.

R code and output

arm    <- c("RedDress Wound Care System (RD1)")
n      <- c(20)
events <- c(20)
for (i in seq_along(n)) {
  ci <- binom.test(events[i], n[i])$conf.int          # Clopper-Pearson exact interval
  cr <- qbeta(c(0.025, 0.975), 1 + events[i], 1 + n[i] - events[i])   # Bayesian, uniform Beta(1,1) prior
  wi <- (function(x, n) { p <- x / n; z <- qnorm(0.975); d <- 1 + z^2 / n
    c((p + z^2 / (2 * n) - z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d, (p + z^2 / (2 * n) + z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d) })(events[i], n[i])
  cat(sprintf("ARM|%s|%d|%d|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f\n", arm[i], n[i], events[i], 100 * events[i] / n[i],
              100 * ci[1], 100 * ci[2], 100 * wi[1], 100 * wi[2], 100 * cr[1], 100 * cr[2]))
}

ARM  RedDress Wound Care System (RD1)  20  20  100.0  83.2  100.0  83.9  100.0  83.9  99.9

11. Multiplicity, Missing Data and Analysis Populations

The registry lists four outcome measures, including the primary adverse-event outcome and secondary outcomes concerning lack-of-venous-access complications, complete wound closure at 12 weeks, and wound-size reduction over 12 weeks. When a study assesses multiple outcomes, there are multiple opportunities for an apparently notable result to arise by chance. In general, a prespecified strategy for handling multiple statistical tests can help readers understand whether and how that issue was addressed. The registry record does not report a multiplicity adjustment or a strategy for prioritizing results beyond identifying the primary outcome.

The record lists no analysis entries. It does not report hypothesis tests, confidence intervals, model specifications, or a detailed statistical analysis plan for the outcomes. Thus, no claim can be made about which analyses were planned, whether they were changed, or whether any adjustment was performed. The absence of reported analyses is not evidence that a particular method was or was not used outside the registry record.

The primary endpoint is identified for the intention-to-treat population, and its description also refers to safety and intention-to-treat populations. A separate result for the safety population is not reported in the registry record. The record does not define population membership or explain how participants with incomplete follow-up were handled. It also does not report the number of participants with missing outcome data, reasons for missingness, or any imputation or sensitivity analysis. The completed status alone does not demonstrate complete outcome ascertainment.

These omissions matter because analysis populations and missing data can affect the interpretation of event counts. Without participant-level flow or clear denominators for each endpoint, readers cannot determine whether all enrolled participants contributed to each reported result. Missing-data methods and population definitions are therefore not reported in the registry record, and no assumptions about them should be made.

12. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 5% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: embolism (5.0%), infection, (5.0%), psychiatric issue (5.0%).

The registry reports 3 participants with serious adverse events and 16 participants with other adverse events in the RD1 group. These are participant counts, not necessarily counts of event episodes. The record does not say whether the same participant may be included in both categories, so the figures should not be added to obtain a total number of unique participants.

Embolism, infection, and psychiatric issue are listed among serious adverse-event terms, each with a recorded percentage of 5.0%. These terms describe events recorded in the registry; they do not establish a causal relationship to RD1. The record does not provide event-level narratives, timing, severity beyond the serious classification, or a separate count of device-related events. Deaths are not reported in the registry record.

Safety counts are most informative when their denominator, follow-up, event definitions, and ascertainment procedures are clear. The primary outcome timeframe is 12 weeks, and the listed endpoint population is intention-to-treat, but a separate safety-population result is not reported. The record does not clarify whether all 20 enrolled participants contributed complete 12-week data. The counts should therefore be understood as the registry’s reported observations, not as precise estimates of risk or proof that the device caused the events.

13. What the Result Does, and Does Not, Mean

The results describe adverse events recorded in a completed, open-label, single-group trial of RD1 in people with Texas 1a or 2a neuropathic diabetic foot ulcers. The registry reports 3 participants with serious adverse events and 16 with other adverse events. It also lists several serious-event terms at 5.0%. These findings provide a record of events observed in the study group during the reported safety assessment.

They do not show how the event counts compare with another intervention or with no RD1 exposure. There was no separate comparator group, and the study was not a randomized comparison. The counts therefore cannot establish whether events occurred more often or less often because of RD1. They also cannot establish that a particular event was caused by the product. The registry’s inclusion of device-related adverse events in the endpoint description is not the same as reporting a separate device-related result.

The results also do not establish the overall safety profile of RD1 in a broad population. The enrolled group contained 20 participants, and the registry does not provide confidence intervals or detailed information about completeness of follow-up. The event counts may be imprecise as estimates of outcomes beyond this trial, and the record does not permit a full assessment of that uncertainty. The study’s completed status does not, on its own, confirm that all participants completed follow-up or that all outcome data were available.

Wound closure and wound-size reduction appear as secondary outcomes in the registry, but no results for those outcomes are included in the record. Their inclusion does not support a conclusion about wound healing. More generally, the study’s safety focus should not be mistaken for evidence of comparative efficacy. The justified interpretation is limited to the outcomes and counts reported: events were recorded in the RD1 group, while comparative safety, causality, and broader generalizability remain unresolved by this single-group record.

14. Why This Trial Matters Statistically

This trial is statistically important because its design makes the boundary between description and comparison especially clear. A single-group study can document events observed while participants receive an intervention. It cannot, on its own, estimate how event occurrence differs from a separate treatment or from an untreated condition. Recognizing that distinction prevents descriptive counts from being mistaken for evidence of a treatment effect.

The safety outcome is expressed as the number of participants experiencing events over 12 weeks. That is a clinically interpretable form of summary, but its interpretation depends on clear event definitions, consistent ascertainment, complete follow-up, and a clear denominator. The registry provides some endpoint definitions and counts but does not report confidence intervals, participant-level follow-up, or a separate safety-population result. These gaps illustrate why the number alone is not a complete statistical description.

The trial also shows why adverse-event categories need careful handling. Serious and other adverse-event counts may overlap, and individual event terms are not equivalent to evidence of causation. Without event-level detail or a comparison group, the figures cannot distinguish among background events, complications related to the underlying condition or care, and events attributable to the device. Statistical reporting should make those distinctions visible wherever the data permit.

Finally, the registry lists secondary outcomes but no analysis entries. The existence of multiple outcomes raises general questions about prespecification, multiplicity, and missing data, yet the record does not report how those issues were handled. Treating unreported methods as unknown rather than assuming standard practice is an important part of transparent trial interpretation. The record’s value is in its description of a small safety study and the questions it leaves open, not in establishing a comparative conclusion.

15. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

The main limitation for interpretation is the absence of a comparator. With a single group and no randomized allocation, the registry results cannot estimate a difference in adverse-event occurrence between RD1 and another approach. They also cannot separate events associated with the intervention from events related to the condition, other care, or background risk.

The enrollment was 20, which limits how much the record can establish about uncommon events and the precision of event estimates. Confidence intervals are not reported in the registry record. A sample-size justification is also not reported, so the enrollment cannot be judged against a stated precision or safety-detection objective. The planning assumptions described in the record relate to a two-arm illustration and should not be treated as the trial’s design or as evidence of observed power.

The open-label design may affect the way outcomes are elicited, reported, or classified in general, but the record does not describe event-adjudication procedures. There is also no detailed account of event timing, duration, recurrence, severity beyond the serious classification, or attribution to the device. The named serious-event terms do not supply this missing context.

The record does not report whether every participant completed the 12-week timeframe, how missing outcomes were handled, or the denominator used for each adverse-event category beyond the group enrollment information. It mentions both intention-to-treat and safety populations in the endpoint description, but separate results for both populations are not reported. The registry lists secondary wound outcomes without results in the record described, and no analysis entries are listed. These limitations constrain both the safety interpretation and any broader conclusions about the intervention.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Safety Trial of the RedDress Wound Care System (RD1) in Management of Texas 1a or 2a Neuropathic Diabetic Foot Ulcers. — NCT01396837.
• Registry record last updated 2020-12-02; status last verified 2020-11.
• Results first posted 2020-11-16.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

19. Record Summary

NCT01396837 is a completed Phase 2, multicenter, prospective, open-label, single-group safety trial of the RedDress Wound Care System (RD1) in people with Texas 1a or 2a neuropathic diabetic foot ulcers. The registry lists enrollment of 20, a start of 2014-05, and primary completion in 2016-08. RD1 is described as a biologic autologous wound care product made from the participant’s whole blood at the point of care using the RD1 kit.

The primary outcome is the number of participants experiencing adverse events over 12 weeks, with the endpoint description covering serious adverse events, other adverse events including lack-of-venous-access events, and device-related adverse events. The record reports 3 participants with serious adverse events and 16 with other adverse events. It lists embolism, infection, and psychiatric issue among serious-event terms at 5.0% each. There is no separate comparator group, and the registry record does not report analysis entries, confidence intervals, missing-data methods, or a separate safety-population result.